1. Field of the Invention
This invention relates to the field of virtual images.
2. Background Art
Many existing entertainment or amusement games rely on a conventional CRT display ("television" display). A player's point of view is trained on the television display. It is difficult for a player to divert attention to anything other than the display .unless the diversion requires only a minimal perspective change. For example, a player would have difficulty remaining attentive to a video game display and making eye contact with another individual unless that individual's face was in close proximity to the video display.
Some games provide a multiple player mode. In multiple player mode, players either alternate "turns" in interacting with the game, or the players sit "side-by-side" and compete against each other, or cooperate against a common opponent. Whether the players are competing against one another or cooperating against a common opponent, it is not possible to see the expressions on each other's faces or determine the position of the other player's line of sight.
Because the players sit side-by-side when using prior art games, direct human interaction is unavailable. Thus, conventional video games are lacking in that players can't directly experience the reactions of their opponents or partners.
For example, Berman, U.S. Pat. No. 4,879,603, provides a way for adjacent users to view different images on a heads up display. The system uses circular polarization to project multiple images. By using appropriate filters (e.g. eyeglasses), each user sees only one of the projected images.
Ricker, U.S. Pat. No. 4,535,354, provides a method for projecting a pair of stereoscopic pictures that can be seen in three dimensions. Two projection images are projected onto a focusing screen. A beam splitter that acts as a reflector and transmitter is positioned between an observer and the focusing screen, or between the source images and the focusing screen. The system can be adapted for multiple users if they are located laterally to each other. There is no discussion of opposing views in Ricker.
Breslow, U.S. Pat. No. 4,710,873, describes a video game apparatus for capturing an image of a user, digitizing the image, and incorporating the image into the video game itself. A camera is included in the cabinetry of the video game and is used for image capture. The captured image is displayed on a prior art type video display.
Rebane, U.S. Pat. No. 3,857,022, provides a system including a positioning table that provides a signal representative of the position of a pen touched to a screen. An image can be projected onto the touch screen from behind, if the screen is translucent, or from the front, if the screen is opaque.
Yokoi, U.S. Pat. No. 4,589,659, is directed to a liquid crystal display that projects an image onto a mirror for viewing. The scheme permits an LCD display to be folded to a compact size and is suitable for portable video game use. The device is for viewing from one side only, or side by side viewing.
A heads up display system with holographic dispersion correction is described in Hartman, U.S. Pat. No. 4,613,200. The invention uses a grating device attached to a windshield and a second grating device under the dash. The device appears to be tuned to be optimized for a driver.
A stereoscopic display that provides alternating left and right images to create the illusion of depth is described in Pund, U.S. Pat. No. 4,649,425. The display is for viewing from one direction only.
A reflected display is described in Japan 1-47422 to Kuwayama. One party can simultaneously view display information and a party opposite a display screen. Unlike the present invention, the purpose of Kuwayama is to prevent the second party from viewing the displayed information. Such a scheme precludes "see through" viewing by two opposing viewers.
An illusion apparatus is described in Weinreich, U.S. Pat. No. 4,971,312. This scheme permits a human viewer to appear to interact with a display such as a television or monitor.
A double sided display of dot matrix LED or LCD display units is described in Shigeta, U.S. Pat. No. 4,973,951. The scheme is not related to video displays. The opposing displays are not see through, but rather opaque members are disposed between the displays.
A heads up display for an automobile or other moving vehicle is described in Roberts, U.S. Pat. No. 5,005,009. The invention is not related to video games.
Yamamura, JP-18588, describes a two direction heads up display device. Viewers on either side of a glass panel can see independent images with virtually no cross-talk between the images. There is no discussion of viewing both displayed images and the opposing viewer simultaneously, or matching the images to provide coincident "points of interest" of the projected images.
Harris, U.S. Pat. No. 5,115,228, describes a shuttered display panel that is viewable from the front and the back simultaneously. A see through display that can be viewed from both the front and back, e.g. a vacuum fluorescent display, is provided. When it is desired to show different images to the front and back users, an image is generated for the front viewer while the rear shutters are closed. A second image is generated for the rear viewer while the front shutters are closed. A video game that matches video display with user speech is described in Edelstein, U.S. Pat. No. 5,149,104.
A method for superimposition of projected and three dimensional objects is described in Lunde, U.S. Pat. No. 4,738,522. The system provides a method for using a beam splitter to combine the movement of an actor on a three dimensional set with a projected image. The beam splitter is provided in front of the three dimensional set. A recorded or live image is projected onto the beam splitter, forming a combined image. The projected image appears to interact with the three dimensional set pieces.
Prior art beam splitter and heads up display techniques have the characteristic of the virtual image being partially transparent. While partial transparency of the virtual image may be desirable in some situations, it is often desirable to provide control over the transparency or opacity of a virtual image. Prior art beam splitter and heads up display techniques have not provided such control.